s390/ftrace: fix mcount adjustment
Tony Jones reported that the ftrace self tests on s390 do not work: <6>Testing dynamic ftrace ops #1: (0 0 0 0 0) FAILED! <6>Testing tracer irqsoff: <3>failed to start irqsoff tracer <4>.. no entries found ..FAILED! <6>Testing tracer wakeup: <3>failed to start wakeup tracer <4>.. no entries found ..FAILED! <6>Testing tracer function_graph: <4>Failed to init function_graph tracer, init returned -19 <4>FAILED! This happens because we forgot to adjust the instruction pointer that gets passed to the ftrace trace function by MCOUNT_INSN_SIZE. In addition change MCOUNT_INSN_SIZE to the correct value on 31 bit. It only worked so far because the to be patched instruction was identical. Reported-by: Tony Jones <tonyj@suse.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -9,11 +9,6 @@ struct dyn_arch_ftrace { };
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#define MCOUNT_ADDR ((long)_mcount)
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#ifdef CONFIG_64BIT
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#define MCOUNT_INSN_SIZE 12
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#else
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#define MCOUNT_INSN_SIZE 20
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#endif
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static inline unsigned long ftrace_call_adjust(unsigned long addr)
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{
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@ -21,4 +16,11 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
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}
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#endif /* __ASSEMBLY__ */
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#ifdef CONFIG_64BIT
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#define MCOUNT_INSN_SIZE 12
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#else
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#define MCOUNT_INSN_SIZE 22
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#endif
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#endif /* _ASM_S390_FTRACE_H */
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@ -16,12 +16,6 @@
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#include <trace/syscall.h>
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#include <asm/asm-offsets.h>
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#ifdef CONFIG_64BIT
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#define MCOUNT_OFFSET_RET 12
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#else
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#define MCOUNT_OFFSET_RET 22
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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void ftrace_disable_code(void);
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@ -155,9 +149,10 @@ unsigned long __kprobes prepare_ftrace_return(unsigned long parent,
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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goto out;
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ip = (ip & PSW_ADDR_INSN) - MCOUNT_INSN_SIZE;
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if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
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goto out;
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trace.func = (ip & PSW_ADDR_INSN) - MCOUNT_OFFSET_RET;
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trace.func = ip;
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/* Only trace if the calling function expects to. */
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if (!ftrace_graph_entry(&trace)) {
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current->curr_ret_stack--;
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@ -7,6 +7,7 @@
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#include <linux/linkage.h>
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#include <asm/asm-offsets.h>
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#include <asm/ftrace.h>
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.section .kprobes.text, "ax"
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@ -33,6 +34,7 @@ ENTRY(ftrace_caller)
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la %r2,0(%r14)
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st %r0,__SF_BACKCHAIN(%r15)
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la %r3,0(%r3)
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ahi %r2,-MCOUNT_INSN_SIZE
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l %r14,0b-0b(%r1)
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l %r14,0(%r14)
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basr %r14,%r14
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@ -7,6 +7,7 @@
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#include <linux/linkage.h>
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#include <asm/asm-offsets.h>
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#include <asm/ftrace.h>
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.section .kprobes.text, "ax"
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@ -29,6 +30,7 @@ ENTRY(ftrace_caller)
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stg %r1,__SF_BACKCHAIN(%r15)
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lgr %r2,%r14
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lg %r3,168(%r15)
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aghi %r2,-MCOUNT_INSN_SIZE
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larl %r14,ftrace_trace_function
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lg %r14,0(%r14)
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basr %r14,%r14
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